1. Field of the Invention
The present invention relates to a magnetic head slider supporting apparatus for flexibly supporting a magnetic head slider that faces toward a recording medium, and to a head gimbal assembly, a head arm assembly and a magnetic disk drive each incorporating the magnetic head slider supporting apparatus.
2. Description of the Related Art
A thin-film magnetic head element used in a magnetic disk drive is provided in a magnetic head slider (which may be hereinafter simply called a slider). The slider is flexibly supported by a suspension and placed to face toward a recording medium. When the recording medium rotates, a lift is exerted on the slider because of an airflow passing between the recording medium and the slider. The slider slightly flies over the medium by means of the lift.
The suspension typically incorporates: a plate-spring-shaped load beam; a flexure to which the slider is joined, the flexure being located at an end of the load beam and giving an appropriate degree of freedom to the slider; and a mounting section provided at the other end of the load beam and attached to an arm for moving the slider across the tracks of the recording medium. An assembly in which the slider is attached to the suspension is called a head gimbal assembly. An assembly in which the head gimbal assembly is attached to a single arm is called a head arm assembly.
A thin-film magnetic head element incorporates a write element for writing data on a recording medium and a read element for reading data from the recording medium. A magnetic disk drive comprises a read/write processing circuit for controlling the write element and the read element. The write element is connected to the read/write processing circuit through two lines while the read element is connected to the read/write processing circuit through another two lines. These four lines in total are located in proximity to one another along the load beam of the suspension. As a result, there is a possibility that parasitic capacitances emerge among these lines and that crosstalk occurs between each of the lines connected to the write element and each of the lines connected to the read element.
If the above-mentioned crosstalk occurs, a relatively large voltage is induced on the lines connected to the read element in response to a great change in voltage of a write signal, and this voltage is applied to the read element. As a result, such a problem arises that electromigration at the read element is accelerated to cause a reduction in the life of the read element and that diffusion of atoms among layers making up the read element is accelerated to cause degradation in the characteristics of the read element. This problem has become particularly noticeable as higher recording density is achieved for magnetic disk drives recently. One of the reasons is that thin-film magnetic head elements are reduced in dimensions as higher recording density is achieved, and the area of a region in which the read element is disposed is reduced and the heat releasing property is thereby reduced, and that the cross-sectional area of the read element is reduced and the current density in the read element is thereby increased. Another one of the reasons is that the frequency of a write signal is increased as higher recording density is achieved, and a change in voltage of the write signal is thereby made abrupt.
According to a technique disclosed in the Published Unexamined Japanese Patent Application 2001-256627, in a head gimbal assembly incorporating a slider, a suspension and lead traces, a parasitic capacitance between the ground and the lead traces is reduced by removing a portion of a load beam and a portion of a flexure located below the lead traces.
The Published Unexamined Japanese Patent Application 2003-308668 discloses a technique in which, in a wiring member used for a suspension, the thickness of a polyimide layer between a metal substrate and conductors is changed and the widths of the conductors are changed, so that the distance between the conductors is increased to reduce crosstalk.
The Published Unexamined Japanese Patent Application 2002-123903 discloses a technique for suppressing crosstalk by applying voltages having nearly symmetric waveforms to two lines connected to a write element.
According to the technique disclosed in the Published Unexamined Japanese Patent Application 2001-256627, it is impossible to reduce a parasitic capacitance between the lines. It is therefore impossible to reduce crosstalk between the lines.
According to the technique disclosed in the Published Unexamined Japanese Patent Application 2003-308668, there is a limit to the distance between the conductors that can be increased. It is therefore difficult to reduce crosstalk effectively.
According to the technique disclosed in the Published Unexamined Japanese Patent Application 2002-123903, it is intended to cancel out voltages wherein one of the voltages is induced on two lines connected to the read element by a voltage spike emerging on one of the lines connected to the write element while the other of the voltages is induced on the two lines connected to the read element by a voltage spike emerging on the other of the lines connected to the write element. In practice, however, there is a difference between the distance from the one of the lines connected to the write element to the two lines connected to the read element and the distance from the other of the lines connected to the write element to the two lines connected to the read element. Consequently, the voltages induced on the two lines connected to the read element by the voltage spikes emerging on the two lines connected to the write element are not equal. Therefore, crosstalk still occurs, according to the technique disclosed in the Published Unexamined Japanese Patent Application 2002-123903.